3Com 3824 Implementation Guide - Page 19

Aggregated Links 19 Aggregated Links Aggregated links are connections that allow devices to communicate using up to eight member links in parallel. Aggregated links provide the following benefits: ■ They can potentially increase the bandwidth of a connection. The capacity of the multiple links is combined into one logical link. ■ They can provide redundancy - if one link is broken, the other links share the traffic for that link. Figure 1 shows two Switches connected using an aggregated link containing four member links. If all ports on both Switch units are configured as 1000BASE-TX and they are operating in full duplex, the potential maximum bandwidth of the connection is 8 Gbps. Figure 1 Switch units connected using an aggregated link . How 802.3ad Link Aggregation Operates Your Switch supports IEEE Std 802.3-2002 (incorporating 802.3ad) aggregated links which use the Link Aggregation Control Protocol (LACP). LACP provides automatic, point-to-point redundancy between two devices (switch-to-switch or switch-to-server) that have full duplex connections operating at the same speed. By default, LACP is disabled on all Switch ports. If a member link in an aggregated link fails, the traffic using that link is dynamically reassigned to the remaining member links in the aggregated link. Figure 2 shows the simplest case: two member links, that is the physical links, form an aggregated link. In this example, if link 1 fails, the data flow between X and B is remapped to physical link 2. The re-mapping occurs as soon as the Switch detects that a member link has